1. Technical Field
This invention relates generally to internal combustion engines, and more particularly to pistons and their method of construction.
2. Related Art
Pistons for internal combustion engines are known to include annular cooling galleries to facilitate maintaining the pistons within operable temperature limits. Once oil is delivered into the cooling gallery through an oil inlet, typically located on one side of the piston, it is desirable to have the oil circulate to an opposite side of the piston and exit through an oil outlet, whereupon the oil typically returns to the crankcase. If the oil is allowed to exit the oil inlet, insufficient cooling of the piston can result, thereby potentially diminishing the useful life of the piston.
Some attempts have been made to prevent the exit of oil through the oil inlet. A known mechanism includes the fixation of a separate annular part to the piston, about the oil inlet, to form an upstanding barrier about the oil inlet to inhibit the egress of oil. Although this can prove effective, the need to perform a secondary attachment process to attach the part to the piston, such as via welding, comes with addition part and manufacturing process costs. Another known attempt includes the formation of a barrier in a casting operation, and again, although this can prove effective, it requires the piston part to be cast, which is not always desirable, depending on the piston application as well as the manufacture process of the piston. Further, casting in the barrier requires special molds for each different form of piston being made, and comes with inherent costs.